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Journal articles on the topic 'Alkali-activation'

Author: Grafiati

Published: 4 June 2021

Last updated: 14 March 2023

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1

Shabanov, O. M., L. A. Kazieva, and Sagim I. Suleymanov. "Activation of Molten Alkali Chloroaluminates." Advanced Materials Research 1033-1034 (October 2014): 477–80. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.477.

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The electrical conductivity of molten sodium and potassium chloroaluminumates increase with increasing electrical field strength and reach the limiting values. The limiting high-voltage conductivities of the melts surpass their usual values up to 200% in NaAlCl4and 700% in KAlCl4. These results have been obtained on the base of analysis of the microsecond high-voltage discharges in the melts (the Wien effect). After the high-voltage pulses discharges having been completed in the melts, their conductivity has been found to rise up to 50% (the “memory effect”). The relaxation time of a non-equilibrium state reaches 5 minutes and more.

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2

Zheng, Guang Jian, Xue Min Cui, Wei Peng Zhang, and Zhang Fa Tong. "Alkali-Activation Reactivity and Al Environment of Chemosynthetic Al₂O₃–2SiO₂ Powders." Advanced Materials Research 79-82 (August 2009): 2079–82. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.2079.

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In this study, pure Al2O3-2SiO2 powders for a geopolymer were prepared by a sol-gel method, alkali-activation tests and alkali-dissolvability of the powders were carried out, and structure of the powders and alkali-activated products was investigated by 29Si and 27Al MAS NMR and SEM. Results showed that higher alkali-activation reactivity (higher compressive strengths of alkali-activated products) appeared in the powders heat-treated between 600-800 °C and alkali-dissolvability trend was different from that of alkali-activation tests. There were clear correlations between microstructure of alkali-activated products and alkali-activation reactivity and Al environment of the powders. It was found that high strength was related to a dense, fine grained microstructure. Such a structure was found in the alkali-activated products synthesized with the powders with high 5-coordinated Al contents. In addition, the peaks attributed to 5-coordinated Al were strengthened with the rise of heat-treated temperature of the powders.

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3

Ge, Wei, Jun Chen, Fanfei Min, Shaoxian Song, and Hui Liu. "Potential Evaluation for Preparing Geopolymers from Quartz by Low-Alkali Activation." Materials 16, no. 4 (February 13, 2023): 1552. http://dx.doi.org/10.3390/ma16041552.

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Alkali fusion of granite sawdust at a high alkali dosage can significantly improve geopolymerization activity, but also result in a high alkali consumption and a poor geopolymer performance. In this work, quartz, the most inert component in granite sawdust, was selected to explore the effect of low-alkali activation on its reactivity and the compressive strength of geopolymer. It was found that the amount of activated quartz is mainly determined by the amount of alkali used for activation. The surface of a quartz particle can be effectively activated by an alkali fusion process at a low alkali dosage of 5%. The metakaolin-based geopolymer synthesized with quartz activated by an alkali dosage of 5% shows a high compressive strength of 41 MPa, which can be attributed to the enhanced interfacial interaction between quartz and the geopolymer gel, suggesting that low-alkali activation is a potential way to improve the geopolymerization ability of granite sawdust.

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4

Huang, Dong, Wan Li Lu, Jin Ying Pang, Guo Wei Mo, Shu Juan Yu, and Guang Jian Zheng. "Effects of Preparation Conditions on Alkali-Activation Reactivity of Chemosynthetic Al₂O₃-2SiO₂ Powders." Advanced Materials Research 1120-1121 (July 2015): 123–27. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.123.

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Pure Al2O3-2SiO2 powders with alkali-activation reactivity were prepared by a sol-gel method. The effects of preparation conditions on alkali-activation reactivity were studied and the optimum preparation conditions were obtained. The results show that calcination temperature is a key factor affecting the alkali-activation reactivity of the powders, while other preparation conditions such as synthetic temperature, the molar ratio of solvents to starting materials and drying time have fewer effects on alkali-activation reactivity than calcination temperature. The structure of the powders was investigated by 27Al magic-angle spinning nuclear magnetic resonance spectra. The data show that the Al2O3-2SiO2 powders with the high alkali-activation reactivity are of high content of 5-coordinated Al and the peaks attributed to 5-coordinated Al are strengthened with the rise of calcination temperature of the powders.

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5

Alharbi, Najat, Richard Hailstone, and Benjamin Varela. "Multiple Phase Identification in Alkali Activated Slag by SEM-EDS." Key Engineering Materials 761 (January 2018): 49–56. http://dx.doi.org/10.4028/www.scientific.net/kem.761.49.

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Alkali-activated slag is studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray microanalysis. Attention is focused on delineating the phases induced by the alkali activation, as these phases are important in determining the mechanical properties of the material. The starting material, slag, is found to be a heterogeneous material with at least two phases. Upon alkali activation the material becomes more heterogeneous, now exhibiting at least four phases with significant different chemical composition. Furthermore, the alkali activation is found to modify the phase rich in Ca in the unactivated slag more than the other. Alkali activation of the slag produced mostly an amorphous material with some crystalline phases such as hydrotalcite and calcite, also some nanocrystalline structures were detected by TEM.

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6

Komnitsas, Konstantinos, Athanasia Soultana, and Georgios Bartzas. "Marble Waste Valorization through Alkali Activation." Minerals 11, no. 1 (January 2, 2021): 46. http://dx.doi.org/10.3390/min11010046.

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In the present study, the valorization potential of marble waste in the presence of metakaolin via alkali activation was explored. The activating solution used consisted of NaOH and sodium silicate solutions. The effects of marble waste to metakaolin ratio, particle size of raw materials, curing temperature, and Na2O/SiO2 and H2O/Na2O molar ratios present in the activating solution on the main properties and the morphology of the produced alkali-activated materials (AAMs) was evaluated. The durability and structural integrity of the AAMs after firing at temperatures between 200 and 600 °C, immersion in deionized water and 1 mol/L NaCl solution for different time periods and subjection to freeze–thaw cycles were also investigated. Characterization techniques including Fourier transform infrared spectroscopy, X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy were used in order to study the structure of the produced AAMs. Τhe highest compressive strength (~36 MPa) was achieved by the AAMs prepared with marble waste to metakaolin mass ratio of 0.3 after curing at 40 °C. The results indicated that the utilization of marble waste in the presence of metakaolin enables the production of AAMs with good physical (porosity, density and water absorption) and mechanical properties, thus contributing to the valorization of this waste type and the reduction of the environmental footprint of the marble industry.

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7

Bakharev, Tatiana, Jay Gnananandan Sanjayan, and Yi-Bing Cheng. "Alkali activation of Australian slag cements." Cement and Concrete Research 29, no. 1 (January 1999): 113–20. http://dx.doi.org/10.1016/s0008-8846(98)00170-7.

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8

Tarantino, Serena Chiara, Roberta Occhipinti, Gennaro Ventruti, and Michele Zema. "Environmental-friendly materials by alkali activation." Acta Crystallographica Section A Foundations and Advances 74, a2 (August 22, 2018): e286-e286. http://dx.doi.org/10.1107/s2053273318090873.

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9

Degtyareva, Valentina F. "Compressed alkali and alkali-earth metals: understanding structure through Jones zone activation." Acta Crystallographica Section A Foundations of Crystallography 66, a1 (August 29, 2010): s200. http://dx.doi.org/10.1107/s0108767310095486.

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10

Joseph, Shiju, Siva Uppalapati, and Ozlem Cizer. "Instantaneous activation energy of alkali activated materials." RILEM Technical Letters 3 (March 12, 2019): 121–23. http://dx.doi.org/10.21809/rilemtechlett.2018.78.

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Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.

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11

Jin, Zi Qiao, Xian Jun Lu, and Shu Gang Hu. "Alkali Activation of Granulated Blast Furnace Slag." Advanced Materials Research 158 (November 2010): 1–11. http://dx.doi.org/10.4028/www.scientific.net/amr.158.1.

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In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

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12

Lancellotti, Isabella, Chiara Ponzoni, Luisa Barbieri, and Cristina Leonelli. "Alkali activation processes for incinerator residues management." Waste Management 33, no. 8 (August 2013): 1740–49. http://dx.doi.org/10.1016/j.wasman.2013.04.013.

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13

Khalifa, Ahmed Z., Özlem Cizer, Yiannis Pontikes, Andrew Heath, Pascaline Patureau, Susan A. Bernal, and Alastair T. M. Marsh. "Advances in alkali-activation of clay minerals." Cement and Concrete Research 132 (June 2020): 106050. http://dx.doi.org/10.1016/j.cemconres.2020.106050.

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14

Sisol, Martin, Juraj Mosej, Miroslava Drabová, and Ivan Brezani. "Effect of Mechanical Activation on Properties of Alkali Activated Binders." Advanced Materials Research 1000 (August 2014): 67–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1000.67.

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Effect of mechanical activation of fly ashes on strength of alkali activated binders is investigated. Four different kinds of fly ashes are mechanically activated. The aim of mechanical activation is to increase the reactivity of fly ashes. Mechanically activated fly ash is used as an admixture to the untreated original fly ash in proportion of 0, 50, 75 and 100 %. Fly ashes are alkali activated with solutions containing sodium hydroxide and sodium water glass. Compressive and flexural strength is tested on hardened alkali activated binders.

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15

Yang, Rui Juan, Ying Hui Wang, and Shi Quan Liu. "The Crystallization of Lithium-Iron-Phosphate Glasses Containing Alkali and Alkali-Earth Metal Oxides." Key Engineering Materials 636 (December 2014): 69–72. http://dx.doi.org/10.4028/www.scientific.net/kem.636.69.

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The crystallization activation energies and crystalline phases of lithium-iron-phosphate (LIP) glasses with alkali and alkali-earth metal oxides have been studied and compared. The results indicate that the alkali and alkali-earth metal oxides reduce the glass crystallization. Moreover, the alkali metal oxides result in the changes in the crystalline phase, while the alkali-earth metal oxides make the glass crystallization more sensitive to the thermal treatment conditions.

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16

Valášková, Marta, Zdeněk Klika, Jozef Vlček, Lenka Matějová, Michaela Topinková, Helena Pálková, and Jana Madejová. "Alkali-Activated Metakaolins: Mineral Chemistry and Quantitative Mineral Composition." Minerals 12, no. 11 (October 23, 2022): 1342. http://dx.doi.org/10.3390/min12111342.

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The reaction products resulting from the alkali-activation of metakaolin are impacted by the composition of the initial kaolin, and amount of alkali-activated kaolinite and water. The present study focused on analyzing these parameters on the metakaolins calcined at 800 °C from three kaolins, and the metakaolins’ alkali activation for 2, 3 and 28 days. The first objective was to evaluate the mineral chemistry and quantitative mineral phase composition from the bulk chemical analysis using the chemical quantitative mineral analysis (CQMA) procedure and conduct a comparison of the chemistry of the metakaolins after alkali activation for 28 days according to the elements Al, Si, Na and K, using the leaching test in distilled water. The second task was to search for possible relationships between the quantitative number of phases in alkali-activated metakaolins and compressive strength. The main methods used for the characterization of material were X-ray fluorescence, X-ray diffraction, thermal TG/DTA and infrared spectroscopy. Metakaolins alkali activated for 28 days contained crystalline quartz, muscovite, orthoclase, and unreacted metakaolinite contained zeolite A (Z-A), hydrosodalite (HS) and thermonatrite (TN) in the amorphous/weakly crystalline phase. The compressive strengths (CS) from 6.42 ± 0.33 to 9.97 ± 0.50 MPa are related positively to H2O+ and H2O bound in HS and TN.

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17

Zhao, Yong-Hua, Jin-Tao Geng, Jie-Chuan Cai, Yu-Fu Cai, and Chun-Yan Cao. "Adsorption performance of basic fuchsin on alkali-activated diatomite." Adsorption Science & Technology 38, no. 5-6 (May 5, 2020): 151–67. http://dx.doi.org/10.1177/0263617420922084.

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The natural diatomite was treated with NaOH to obtain alkali-activated diatomite. The materials were systematically characterized by X-ray powder diffraction, X-ray fluorescence, Fourier transform infrared spectroscopic, scanning electron microscopy, and N2 adsorption–desorption. Meanwhile, the potential use of alkali-activated diatomite as adsorbent for the removal of basic fuchsin from aqueous solution was assessed by batch experiment. Results indicated that the structure and textural properties of diatomite were obviously changed via alkali activation, and then affecting its adsorption performance. The adsorption capacity of alkali-activated diatomite for basic fuchsin was higher than that of natural diatomite. In the case of alkali-activated diatomite, its adsorption capacity was increased with increasing the activation temperature, and the diatomite activated at 115°C (alkali-activated diatomite-115) exhibited the maximum adsorption capacity. The pseudo-first-order kinetics and the Sips isotherm model were preferable to describe the adsorption process of basic fuchsin on alkali-activated diatomite-115 and the thermodynamic parameters indicated that the adsorption process was endothermic and spontaneous.

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18

Kioupis, Dimitris, AggelikiSkaropoulou, Sotiris Tsivilis, and GlikeriaKakali. "Alkali leaching control of construction and demolition waste based geopolymers." MATEC Web of Conferences 149 (2018): 01064. http://dx.doi.org/10.1051/matecconf/201814901064.

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This study regards the synthesis of waste brick geopolymers and the evaluation of their alkali leaching potential. Geopolymers with varied alkali to Al molar ratios were prepared and their alkali leaching potential was measured. In order to improve the efflorescence of the waste brick geopolymers, KOH was used instead of NaOH in the activation solution, Ca cations were incorporated through the partial substitution of the brick powder by ground granulated blast furnace slag or extra Al was introduced in the activation solution. The results showed that the leachability of the products is close related to the alkali content of the activation solution while the use of K ions in the starting mixtures reduced the leachability potential. The same effect was observed in the case of the extra Al ions incorporation. The partial substitution of the wastes bricks by slag showeda slight increase of leachability even though denser materials with enhanced strengths were prepared.

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19

Steudel, A., D. Mehl, and K. Emmerich. "Simultaneous thermal analysis of different bentonite–sodium carbonate systems: an attempt to distinguish alkali-activated bentonites from raw materials." Clay Minerals 48, no. 1 (March 2013): 117–28. http://dx.doi.org/10.1180/claymin.2013.048.4.08.

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AbstractAlkali activation with sodium carbonates is a traditional method to improve bentonite properties for a variety of applications. In some applications, natural sodium-rich bentonites are preferred, and custom regulations require proper declaration of Na-rich bentonites, with respect to activation. Consequently, there is need for a method that can unambiguously distinguish between natural and activated Na-rich bentonites.The paper deals with the preparation of several alkali-activated sets, specifically (a) anhydrous Na2CO3 with trace amounts of thermonatrite (Na2CO3.H2O) and trona (Na3(CO3)(HCO3).2H2O), hereafter called ASC, (b) mixtures of ASC with CaCO3, and (c) mixtures of ASC with CaCO3 and a Ca2+-rich bentonite at different moisture contents, to distinguish natural and alkali-activated bentonites by simultaneous thermal analysis (STA) linked with a mass spectrometer for the analysis of evolved gases. STA linked with MS revealed alkali activation of bentonites, even in the presence of CaCO3. The moisture content during activation and storage of activated samples, however, has a strong influence on the detection of activated samples by STA-MS. Uncertainties remain with respect to unknown foreign phase contents of technical ASC used for alkali activation in practice and the influence of carbonates like dolomite or siderite, which are often present in natural bentonites.

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20

Aziz, Ikmal Hakem, Khairunnisa Zulkifly, Konstantinos Sakkas, Dimitrios Panias, Georgia Maria Tsaousi, Mohd Mustafa Abdullah Al Bakri, and Heah Cheng Yong. "The Characterization of Steel Slag by Alkali Activation." OALib 04, no. 11 (2017): 1–13. http://dx.doi.org/10.4236/oalib.1103816.

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21

Hamadi, A., and K. Nabih. "Alkali Activation of Oil Shale Ash Based Ceramics." E-Journal of Chemistry 9, no. 3 (2012): 1373–88. http://dx.doi.org/10.1155/2012/769532.

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Timahdit oil shale was subjected to firing transformation via ceramics processing followed by alkali activation to synthesis a materials combining the mechanical properties of ceramics and Zeolites. The mineralogical transformations during firing oil shale have been studied. The main crystalline phases found in oil shale ash (OSA) were wollastonite, gehlenite and augite. Modified oil shale ash (MOSA) was obtained with HNO3acid-leaching in the aim to diminish Ca content. Our experimental approach required a NaOH alkaline activating solution with different concentrations (0.5; 1; 2; 4; 6 and 8M). In our study, X-ray diffraction (XDR), Fourier transform infrared (FTIR) and SEM/EDS analysis were used to evaluate the effect of alkali activation on the structural arrangement of the starting materials (OSA and MOSA) in our study. The quantity and the type of the produced zeolites depended critically on the starting materials and on the NaOH concentration.

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22

Rajamma, Rejini, João A. Labrincha, and Victor M. Ferreira. "Alkali activation of biomass fly ash–metakaolin blends." Fuel 98 (August 2012): 265–71. http://dx.doi.org/10.1016/j.fuel.2012.04.006.

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23

Krivenko, Pavel, Myroslav Sanytsky, and Tetiana Kropyvnytska. "Alkali-Sulfate Activated Blended Portland Cements." Solid State Phenomena 276 (June 2018): 9–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.276.9.

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Early strength of the blended Portland cements containing granulated blast furnace slag and natural pozzolanas (zeolite tuff, etc.) can be enhanced by the alkali-sulfate activation. High early strength of the blended Portland cements as a result of alkali-sulfate activation can be attributed to acceleration of pozzolanic reaction at the early stages and formation of more quantities of ettringite at the early stages of structure formation. The results of the study showed that with high amounts of sodium sulfate in the alkali-sulfate activator, contents of gypsum dihydrate as a setting regulator of the blended Portland cements could be reduced. The effect of sodium sulfate activator on properties of the blended Portland cements was studied and the results are discussed.

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24

A. Saeed1, Saba, and Dunya E. AL-Mammar2. "ADSORPTION POTENTIAL FOR A MIXTURE OF CHEMICALLY AND THERMALLY TREATED CLAYS TO REMOVE ORANGE G DYE FROM WASTE-WATER." iraq journal of market research and consumer protection 13, no. 2 (December 31, 2021): 10–31. http://dx.doi.org/10.28936/jmracpc13.2.2021.(2).

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This study examined the adsorption behavior of anionic dye (orange G) from aqueous solution onto the raw and activated a mixture of illite, kaolinite and chlorite clays from area of Zorbatiya (east of Iraq).The chemical treatment involved alkali and acid activation. The alkali activation obtained by treated the raw clay (RC) with 5M NaOH (ACSO) and the acid activation founded by treated it with 0.25M HCl (ACH) and 0.25M H_2 〖SO〗_4 (ACS). The thermal treatment carried out by calcination the produce activated clay at 750oC for acid activation and 105oC for alkali activation. Batch adsorption method was used to study the adsorption of orange G dye onto raw and activated clays. The impact of different factors related to the adsorption process was studied such as: agitation time, clay dosage, solution pH, starting OG dye concentration, temperature and ionic strength. The adsorption process was described by using Langmuir, Freundlich, Temkin and Dubinin-Raduchkevish isotherm models. Thermodynamic functions like change in enthalpy〖∆H〗^°, change in entropy 〖∆S〗^° and change in Gibbs free energy 〖∆G〗^°were estimated based on Vanʼt Hoff equation.

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25

Bulychev, Boris, Anatolii Dityat'ev, Sergei Ionov, Vladimir Kulbachinskii, Vladimir Kytin, and Valeri Bezmelnitsin. "Synthesis of Fullerides of Alkali and Alkali-Earth Metals under Mechanical and Chemical Activation." Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 310, no. 1 (February 1998): 149–54. http://dx.doi.org/10.1080/10587259808045328.

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26

Komnitsas, Konstantinos, Georgios Bartzas, Vasiliki Karmali, and Evangelos Petrakis. "Factors Affecting Alkali Activation of Laterite Acid Leaching Residues." Environments 8, no. 1 (January 10, 2021): 4. http://dx.doi.org/10.3390/environments8010004.

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In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for 2 h or mixed with metakaolin (MK) in order to increase their reactivity. The effect of several parameters, namely the H2O/Na2O and SiO2/Na2O ratios present in the activating solution, the pre–curing time (4–24 h), the curing temperature (40–80 °C), the curing time (24 or 48 h), and the ageing period (7–28 days) on the properties of the produced alkali activated materials (AAMs), including compressive strength, porosity, water absorption, and density, was explored. Analytical techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and elemental mapping analysis were used for the identification of the morphology and structure of the final products. The experimental results show that the laterite acid leaching residues cannot be alkali activated in an unaltered state, and the compressive strength of the produced AAMs barely reaches 1.4 MPa, while the mixing of the residues with 10 wt% metakaolin results in noticeably higher compressive strength (41 MPa). Moreover, the calcination of residues at 800 and 1000 °C has practically no beneficial effect on alkali activation. Alkali activated materials produced under the optimum synthesis conditions were subjected to high temperature firing for 2 h and immersed in distilled water or acidic solution (1 mol L−1 HCl) for 7 and 30 days in order to assess their structural integrity under different environmental conditions. This study explores the potential of alkali activation of laterite leaching residues amended with the addition of metakaolin for the production of AAMS that can be used as binders or in several construction applications in order to enable their valorization and also improve the environmental sustainability of the metallurgical sector.

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27

Komnitsas, Konstantinos, Georgios Bartzas, Vasiliki Karmali, and Evangelos Petrakis. "Factors Affecting Alkali Activation of Laterite Acid Leaching Residues." Environments 8, no. 1 (January 10, 2021): 4. http://dx.doi.org/10.3390/environments8010004.

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In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for 2 h or mixed with metakaolin (MK) in order to increase their reactivity. The effect of several parameters, namely the H2O/Na2O and SiO2/Na2O ratios present in the activating solution, the pre–curing time (4–24 h), the curing temperature (40–80 °C), the curing time (24 or 48 h), and the ageing period (7–28 days) on the properties of the produced alkali activated materials (AAMs), including compressive strength, porosity, water absorption, and density, was explored. Analytical techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and elemental mapping analysis were used for the identification of the morphology and structure of the final products. The experimental results show that the laterite acid leaching residues cannot be alkali activated in an unaltered state, and the compressive strength of the produced AAMs barely reaches 1.4 MPa, while the mixing of the residues with 10 wt% metakaolin results in noticeably higher compressive strength (41 MPa). Moreover, the calcination of residues at 800 and 1000 °C has practically no beneficial effect on alkali activation. Alkali activated materials produced under the optimum synthesis conditions were subjected to high temperature firing for 2 h and immersed in distilled water or acidic solution (1 mol L−1 HCl) for 7 and 30 days in order to assess their structural integrity under different environmental conditions. This study explores the potential of alkali activation of laterite leaching residues amended with the addition of metakaolin for the production of AAMS that can be used as binders or in several construction applications in order to enable their valorization and also improve the environmental sustainability of the metallurgical sector.

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28

Turan, Canan, Akbar A. Javadi, Raffaele Vinai, and Giacomo Russo. "Effects of Fly Ash Inclusion and Alkali Activation on Physical, Mechanical, and Chemical Properties of Clay." Materials 15, no. 13 (July 1, 2022): 4628. http://dx.doi.org/10.3390/ma15134628.

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This study investigated the improvement in the behaviour of a clay soil due to the addition of alkali-activated fly ash as a stabilising agent, and the effects of different activation factors such as alkali dosages and silica moduli. The alkali activator solution used was a mixture of sodium silicate and sodium hydroxide. Class F fly ash was used as the precursor material for the geopolymerisation process. Soil samples stabilised with non-activated class F fly ash were prepared and tested to compare the results with samples stabilised with alkali-activated fly ash. Compaction tests, unconfined compressive strength tests, X-ray diffraction analysis, and scanning electron microscopy analysis were carried out on samples cured 1, 7, and 28 days at room conditions. The results showed that the compressive strength of stabilised soil significantly increased when the fly ash was activated. The optimal activation parameters to stabilise the soil were found to be alkali dosages in the range of 12% to 16% and a silica modulus of 1.25. The highest compressive strength recorded was at 1293 kPa with an alkali dosage of 16% and a silica modulus of 1.25, while for the non-stabilised soil, it was at 204 kPa at 28 days of curing. Mineralogical analysis showed a decrease in the peak intensities of kaolinite and illite, while microstructural analysis indicated an alteration in soil texture with the addition of the alkali-activated fly ash.

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29

Kljajevic, Ljiljana, Miljana Mirkovic, Sabina Dolenec, Katarina Ster, Mustafa Hadzalic, Ivana Vukanac, and Milos Nenadovic. "Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry." Nuclear Technology and Radiation Protection 36, no. 2 (2021): 182–91. http://dx.doi.org/10.2298/ntrp2102182k.

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The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

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30

Kljajevic, Ljiljana, Miljana Mirkovic, Sabina Dolenec, Katarina Ster, Mustafa Hadzalic, Ivana Vukanac, and Milos Nenadovic. "Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry." Nuclear Technology and Radiation Protection 36, no. 2 (2021): 182–91. http://dx.doi.org/10.2298/ntrp2002182k.

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The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

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31

Mahmoud, Mokhtar, Jozef Kraxner, Hana Kaňková, Miroslava Hujová, Si Chen, Dušan Galusek, and Enrico Bernardo. "Porous Glass Microspheres from Alkali-Activated Fiber Glass Waste." Materials 15, no. 3 (January 28, 2022): 1043. http://dx.doi.org/10.3390/ma15031043.

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Fiber glass waste (FGW) was subjected to alkali activation in an aqueous solution with different concentrations of sodium/potassium hydroxide. The activated materials were fed into a methane–oxygen flame with a temperature of around 1600 °C. X-ray diffraction analysis confirmed the formation of several hydrated compounds, which decomposed upon flame synthesis, leading to porous glass microspheres (PGMs). Pore formation was favored by using highly concentrated activating alkali solutions. The highest homogeneity and yield of PGMs corresponded to the activation with 9 M KOH aqueous solution.

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32

Aziz, Ikmal Hakem, Mohd Mustafa Al Bakri Abdullah, Mohd Arif Anuar Mohd Salleh, Liew Yun Ming, Long Yuan Li, Andrei Victor Sandu, Petrica Vizureanu, Ovidiu Nemes, and Shaik Numan Mahdi. "Recent Developments in Steelmaking Industry and Potential Alkali Activated Based Steel Waste: A Comprehensive Review." Materials 15, no. 5 (March 6, 2022): 1948. http://dx.doi.org/10.3390/ma15051948.

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The steel industry is responsible for one-third of all global industrial CO2 emissions, putting pressure on the industry to shift forward towards more environmentally friendly production methods. The metallurgical industry is under enormous pressure to reduce CO2 emissions as a result of growing environmental concerns about global warming. The reduction in CO2 emissions is normally fulfilled by recycling steel waste into alkali-activated cement. Numerous types of steel waste have been produced via three main production routes, including blast furnace, electric arc furnace, and basic oxygen furnace. To date, all of the steel waste has been incorporated into alkali activation system to enhance the properties. This review focuses on the current developments over the last ten years in the steelmaking industry. This work also summarizes the utilization of steel waste for improving cement properties through an alkali activation system. Finally, this work presents some future research opportunities with regard to the potential of steel waste to be utilized as an alkali-activated material.

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33

Peirce, Sara, Luciano Santoro, Salvatore Andini, Fabio Montagnaro, Claudio Ferone, and Raffaele Cioffi. "Clay sediment geopolymerization by means of alkali metal aluminate activation." RSC Advances 5, no. 130 (2015): 107662–69. http://dx.doi.org/10.1039/c5ra22140d.

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34

Hwang, Su-Hyun, Sang-in Choi, Hae-Woo Park, and Young-Min Jo. "Alkali activation of activated carbon fiber for CO2 adsorption." Journal of Odor and Indoor Environment 14, no. 1 (March 30, 2015): 41–49. http://dx.doi.org/10.15250/joie.2015.14.1.41.

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35

Bole, Leonie J., and Eva Hevia. "Activation of polar organometallic reagents with alkali-metal alkoxides." Nature Synthesis 1, no. 3 (March 2022): 195–202. http://dx.doi.org/10.1038/s44160-022-00040-5.

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36

Du, Bao Li, Xing Hua Fu, Wen Hong Tao, and Xin Jin. "Study on Hydraulicity and Alkali Activation of Ferroalloy Slag." Key Engineering Materials 575-576 (September 2013): 323–26. http://dx.doi.org/10.4028/www.scientific.net/kem.575-576.323.

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The paper studied that the activity, hydraulicity and Alkali Activation of ferroalloy slag compared to granulated ground blast furnace slag, and a further discussion was carried on ferroalloy slag used as addition of cement. The result shows that the activity index meet national standard and has a well Hydraulicity. Moreover,Ca(OH)2 has a great activition to ferroalloy slag.

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37

Takács, E., L. Wojnárovits, Cs Földváry, J. Borsa, and I. Sajó. "Radiation activation of cotton-cellulose prior to alkali treatment." Research on Chemical Intermediates 27, no. 7-8 (October 2001): 837–45. http://dx.doi.org/10.1163/15685670152622103.

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38

Mukhopadhyay, Anal K., Chang-Seon Shon, and Dan G. Zollinger. "Activation Energy of Alkali–Silica Reaction and Dilatometer Method." Transportation Research Record: Journal of the Transportation Research Board 1979, no. 1 (January 2006): 1–11. http://dx.doi.org/10.1177/0361198106197900102.

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39

Zheng, Yujing, Yue Lian, Dawei Wang, Chaolei Ban, Jing Zhao, and Huaihao Zhang. "3D fungi carbon by less-alkali activation for supercapacitors." Vacuum 181 (November 2020): 109746. http://dx.doi.org/10.1016/j.vacuum.2020.109746.

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40

Yang, Xiaoguang, Wen Ni, Xufang Zhang, and Yali Wang. "Effect of alkali-activation on aluminosilicate-based cementitious materials." Journal of University of Science and Technology Beijing, Mineral, Metallurgy, Material 15, no. 6 (December 2008): 796–801. http://dx.doi.org/10.1016/s1005-8850(08)60290-x.

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41

Ingram, Malcolm D., Corrie T. Imrie, and Ioannis Konidakis. "Activation volumes and site relaxation in mixed alkali glasses." Journal of Non-Crystalline Solids 352, no. 30-31 (September 2006): 3200–3209. http://dx.doi.org/10.1016/j.jnoncrysol.2006.05.009.

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42

Marsh, A., A. Heath, P. Patureau, M. Evernden, and P. Walker. "Phase formation behaviour in alkali activation of clay mixtures." Applied Clay Science 175 (July 2019): 10–21. http://dx.doi.org/10.1016/j.clay.2019.03.037.

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43

Jiang, Tao, Guanghui Li, Guanzhou Qiu, Xiaohui Fan, and Zhucheng Huang. "Thermal activation and alkali dissolution of silicon from illite." Applied Clay Science 40, no. 1-4 (June 2008): 81–89. http://dx.doi.org/10.1016/j.clay.2007.08.002.

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44

Xu, Maotong, Andrew R. Jupp, Zheng-Wang Qu, and Douglas W. Stephan. "Alkali Metal Species in the Reversible Activation of H2." Angewandte Chemie 130, no. 34 (July 20, 2018): 11216–20. http://dx.doi.org/10.1002/ange.201806849.

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45

Radwan, M. M., L. M. Farag, S. A. Abo-El-Enein, and H. K. Abd El-Hamid. "Alkali activation of blended cements containing oil shale ash." Construction and Building Materials 40 (March 2013): 367–77. http://dx.doi.org/10.1016/j.conbuildmat.2012.11.006.

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46

Adesanya, Elijah, Katja Ohenoja, Paivo Kinnunen, and Mirja Illikainen. "Alkali Activation of Ladle Slag from Steel-Making Process." Journal of Sustainable Metallurgy 3, no. 2 (September 15, 2016): 300–310. http://dx.doi.org/10.1007/s40831-016-0089-x.

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47

Xu, Maotong, Andrew R. Jupp, Zheng-Wang Qu, and Douglas W. Stephan. "Alkali Metal Species in the Reversible Activation of H2." Angewandte Chemie International Edition 57, no. 34 (July 20, 2018): 11050–54. http://dx.doi.org/10.1002/anie.201806849.

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48

Purbasari, Aprilina, Dessy Ariyanti, Siswo Sumardiono, Muhammad Shofa, and Reinhard Manullang. "Comparison of alkali modified fly ash and alkali activated fly ash as Zn(II) ions adsorbent from aqueous solution." Science of Sintering 54, no. 1 (2022): 49–58. http://dx.doi.org/10.2298/sos2201049p.

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Fly ash which is solid waste can be used as an adsorbent for wastewater treatment. Alkali modification and alkali activation on fly ash can increase the adsorption capacity of fly ash. In this study, alkali modified fly ash and alkali activated fly ash were used as Zn(II) ions adsorbents. The effect of adsorption time and initial concentration of Zn(II) ions was studied, as well as the kinetics and isotherm adsorption. The results showed that the removal efficiency of Zn(II) ions by alkali activated fly ash is higher than that by alkali modified fly ash. The adsorptions of Zn(II) ions by alkali modified fly ash and by alkali activated fly ash have reached equilibrium after two hours. The increase of initial concentration of Zn(II) ions would decrease the removal efficiency with both alkali modified fly ash and alkali activated fly ash. Adsorptions of Zn(II) ions by both alkali modified fly ash and alkali activated fly ash tend to follow pseudo second order kinetics model and Langmuir isotherm model with maximum adsorption capacity of 62.696 mg/g and 66.667 mg/g, respectively.

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49

Qiu, Pengxiang, Fengling Liu, Chenmin Xu, Huan Chen, Fang Jiang, Yang Li, and Zhaobing Guo. "Porous three-dimensional carbon foams with interconnected microchannels for high-efficiency solar-to-vapor conversion and desalination." Journal of Materials Chemistry A 7, no. 21 (2019): 13036–42. http://dx.doi.org/10.1039/c9ta00041k.

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50

Biel, Oliwia, Piotr Rożek, Paulina Florek, Włodzimierz Mozgawa, and Magdalena Król. "Alkaline Activation of Kaolin Group Minerals." Crystals 10, no. 4 (April 2, 2020): 268. http://dx.doi.org/10.3390/cryst10040268.

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Zeolites can be obtained in the process of the alkali-activation of aluminosilicate precursors. Such zeolite–geopolymer hybrid bulk materials merge the advantageous properties of both zeolites and geopolymers. In the present study, the effect of the type and concentration of an activator on the structure and properties of alkali-activated metakaolin, and metahalloysite was assessed. These two different kaolinite clays were obtained by the calcination of kaolin and halloysite, and then activated with sodium hydroxide and water glass. The phase compositions were assessed by X-ray diffraction, the microstructure was observed via scanning electron microscope, and the structural studies were conducted on the basis of the infrared spectra. The structure and properties of the obtained alkali-activated materials depend on both the type of a precursor and the type of an activator. The formation of zeolite phases was observed when the activation was carried out with sodium hydroxide alone, or with a small addition of water glass, regardless of the starting material used. The higher proportion of silicon in the activator solution does not give crystalline phases, but only an amorphous phase. Geopolymers based on metahalloysite have better compressive strength as the result of the better reactivity of metahalloysite compared to metakaolin.

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